Well, there you go, that certainly is the fault of the machine/software.
By the way, considering the ( less now ) price premium on Apple, shouldn't you compare machine's of equal value, such like Sony, or HP PC's, vs the complaints form say low end corporate Dell's or off brand machines. ( Although I bought some e-Machines for a bar for the patrons to destroy and they've worked fine for the usual email, facebook....stuff. They were, the dirt cheapest box I could find, under two hundred dollars. ) Now would you supply a new Apple box for that physical/use application? No you could not.
It certainly is. Macs don't need anti-viral ware... as of this time the total number of Viruses for Mac OS X in the wild, after ten years of OS X being in the wild, is ZERO. The business would not have lost a week of productivity due to viral infection if they had a Mac in that location. EVERYTHING that was being done on that computer could just as easily be done on a Mac... and even the Windows vertical solution database they run the optometry Office software on, being that it does not have to connect to the internet, could be run in a virtual machine sandbox under OS X, and be safe. All other work, especially internet ordering etc., could be handled by the Mac side... and be safely done without the need for cycle eating anti-anything ware.